diff --git a/index.html b/index.html
index cf22f11..7cc3752 100644
--- a/index.html
+++ b/index.html
@@ -173,11 +173,11 @@
                 <div class="inline-flex">
                     <div class="pure-u-1-2">
                         <label for="offset">Offset</label>
-                        <input id="offset" class="slicing local-only pure-u-23-24" type="number" min="0" disabled/>
+                        <input id="offset" class="slicing local-only pure-u-23-24" type="number" min="0" value="0" disabled/>
                     </div>
                     <div class="pure-u-1-2">
                         <label for="limit">Max. (limit)</label>
-                        <input id="limit" class="slicing local-only pure-u-23-24" type="number" readonly disabled/>
+                        <input id="limit" class="slicing local-only pure-u-23-24" type="number" min="0" value="0" readonly disabled/>
                     </div>
                 </div>
             </div>
@@ -188,8 +188,8 @@
 <script type="module">
 import { default as $, LogRecord, Rpc2 } from '/';
 
-let limit = 0;
-let length = 0;
+let major = 0;
+let minor = 0;
 let busy = false;
 let status = null;
 let locale = null;
@@ -199,7 +199,7 @@ let filereader = null;
 let subcategories = [];
 
 window.addEventListener('beforeunload', (e) => {
-    writable?.abort().catch(() => void 0);
+    writable?.abort();
     Rpc2.notify('exit');
     e.preventDefault();
     e.returnValue = '';
@@ -234,7 +234,7 @@ async function handlePrimaryButtonClick() {
 
             let [file, buffer] = await filereader().catch(e => alert('(ERROR) ' + new String(e ?? 'Unable to read data')));
             writable = await handle.createWritable().catch(() => null);
-            limit = await Rpc2.invoke('ready', file.name, new Uint8Array(buffer).toBase64());
+            major = await Rpc2.invoke('ready', file.name, new Uint8Array(buffer).toBase64());
             $.get('#fileLabel').innerText = file.name;
             $.get('#fromLabel').innerText = parameters.account;
             $.all('.columns').forEach(e => e.dispatchEvent(new Event('change')));
@@ -265,7 +265,7 @@ async function handlePrimaryButtonClick() {
 
             if (options.slice) {
                 options.start = $('#offset').valueAsNumber * $('#chunksize').valueAsNumber + 2;
-                options.limit = length;
+                options.limit = Math.min(minor || major, $('#chunksize').valueAsNumber);
                 options.subcategories = subcategories.length > 0 ? subcategories: null;
             }
 
@@ -374,26 +374,19 @@ $.set('#groupby', 'change', (e) => {
 $.set('#subcategory', 'change', (e) => {
     if (!unique) return;
     subcategories = Array.from(e.target.options).filter(o => o.selected).map(o => o.value);
-    length = Object.entries(unique).filter(([k]) => subcategories.includes(k)).reduce((o, [_, v]) => o + v, 0);
+    minor = Object.entries(unique).filter(([k]) => subcategories.includes(k)).reduce((o, [_, v]) => o + v, 0);
     $('#chunksize').dispatchEvent(new Event('change'));
 });
 
 $.set('#chunksize', 'change', (e) => {
-    let n = length || limit;
-    let size = Math.floor(n / e.target.valueAsNumber);
-    $('#limit').value = size;
-    $('#offset').max = size;
+    let limit = minor || major - 1;
+    let value = Math.floor(limit / e.target.valueAsNumber);
+    $('#limit').value = value;
+    $('#offset').max = value;
     $('#offset').value = 0;
     $('#offset').dispatchEvent(new Event('change'));
 });
 
-$.set('#offset', 'change', (e) => {
-    let n = length || limit;
-    let size = $('#chunksize').valueAsNumber;
-    let offset = n - size * e.target.valueAsNumber;
-    length = Math.min(size, offset);
-});
-
 for (let item of Array.from(locales)) {
     $('#locale').add(new Option(item.name.toUpperCase(), item.name));
     $('#locale').dispatchEvent(new Event('change'));
@@ -455,16 +448,21 @@ while (await new Promise(o => setTimeout(o, 1000, true))) {
             $('#send').classList.add('pulse');
             $('#timezoneLabel').innerText = Temporal.Now.zonedDateTimeISO(locale.timezone).toLocaleString(locale.name);
 
-            let { done, email, subject, recipient } = await Rpc2.invoke('progress').catch(() => new Object());
-            $('#progressLabel').innerText = `${parseFloat(done / (length || limit) * 100).toFixed(2)}% (${done}/${length || limit})`
+            let { done, skip, email, subject, recipient } = await Rpc2.invoke('progress').catch(() => new Object());
+            let index = done + skip;
+            let limit = minor || major - 1;
+            let chunk = $('#chunksize').valueAsNumber;
+            let total = $('#slice').checked ? Math.min(chunk, limit - chunk * $('#offset').valueAsNumber) : limit;
+
+            $('#progressLabel').innerText = `${parseFloat(index / total * 100).toFixed(2)}% (${index}/${total})`
             $('#subjectLabel').innerText = subject ?? '';
             $('#recipientLabel').innerText = recipient ? `${recipient} <${email}>` : email ?? '';
 
             let uptime = await Rpc2.invoke('uptime').catch(() => 0);
             $('#uptimeLabel').innerText = Temporal.Duration.from({ seconds: uptime }).round({ largestUnit: 'hours' }).toLocaleString('en', { style: 'digital' });
 
-            let rate = done / uptime
-            let remaining = done ? Math.floor(((length || limit) - done) / rate) : 0;
+            let rate = index / uptime
+            let remaining = index ? Math.floor((total - index) / rate) : 0;
             $('#remainingLabel').innerText = remaining ? `${Temporal.Duration.from({ seconds: remaining }).round({ largestUnit: 'hours' }).toLocaleString('en')} (${rate.toFixed(2)}/min)` : '';
             break;
         case 'STANDBY':
diff --git a/main.py b/main.py
index ffa8c91..2ea5111 100644
--- a/main.py
+++ b/main.py
@@ -283,9 +283,9 @@ def main(driver: Chrome, logger = logging.getLogger('main')):
     flow.append(Skip)
 
     sp.set('actions', lambda: flow.capabilities())
-    sp.set('cancel', lambda: flow.do(Cancel, force=True))
-    sp.set('close', lambda: flow.do(Close, force=True))
-    sp.set('skip', lambda: flow.do(Skip, force=True))
+    sp.set('cancel', lambda: flow.queue(Cancel))
+    sp.set('close', lambda: flow.queue(Close))
+    sp.set('skip', lambda: flow.queue(Skip))
 
     def loads(name: str, b64: str):
         from base64 import b64decode
@@ -353,9 +353,7 @@ def main(driver: Chrome, logger = logging.getLogger('main')):
 
     while True:
         try:
-            flow.allow(Wait)
-            flow.do(Wait)
-            flow.react()
+            flow.react(Wait)
             progress.clear()
             driver.switch_to.window(driver.window_handles[1])
             subject = get_subject()
@@ -377,16 +375,13 @@ def main(driver: Chrome, logger = logging.getLogger('main')):
             logger.info('Timezone: %s', locale.timezone)
 
             progress['done'] = 0
+            progress['skip'] = 0
             progress['subject'] = subject
             logger.info('Done')
         except Cancel:
             status = Status.IDLE
             driver.switch_to.window(driver.window_handles[0])
             continue
-        except StopIteration:
-            logger.error('Invalid locale: %s', options.get('locale'))
-            status = Status.IDLE
-            continue
         except Exception as e:
             logger.error('Error while loading data', exc_info=e)
             status = Status.IDLE
@@ -399,8 +394,7 @@ def main(driver: Chrome, logger = logging.getLogger('main')):
 
         while index <= limit:
             try:
-                flow.do(Wait)
-                flow.react()
+                flow.react(Wait)
                 attempts += 1
                 name = cell(index, column.recipient).value
                 email = cell(index, column.email).value
@@ -447,8 +441,7 @@ def main(driver: Chrome, logger = logging.getLogger('main')):
 
                 flow.allow(Cancel)
                 flow.allow(Skip)
-                flow.do(Wait)
-                flow.react()
+                flow.react(Wait)
                 progress['email'] = str(email)
                 progress['recipient'] = str(name)
                 logger.info('[%d/%d] Sending to %s', index-1, limit-1, email)
@@ -464,8 +457,7 @@ def main(driver: Chrome, logger = logging.getLogger('main')):
                 if error is not None and not options.get('force'):
                     raise error
 
-                flow.do(Wait)
-                flow.react()
+                flow.react(Wait)
                 click("ul.classic-toolbar button[aria-label='Edit copy']")
                 until(ready)
                 locate("div.io-ox-mail-compose-window iframe", condition=EC.frame_to_be_available_and_switch_to_it)
@@ -495,8 +487,7 @@ def main(driver: Chrome, logger = logging.getLogger('main')):
                         clean = target.text == hello
 
                 driver.switch_to.default_content()
-                flow.do(Wait)
-                flow.react()
+                flow.react(Wait)
                 click("div.io-ox-mail-compose-window div[data-extension-id='to'] > div.mail-input")
                 box = locate("div.io-ox-mail-compose-window div[data-extension-id='to'] > div.mail-input input.token-input.tt-input[tabindex='0']")
                 box.send_keys(str(email) + Keys.ENTER)
@@ -514,8 +505,7 @@ def main(driver: Chrome, logger = logging.getLogger('main')):
                     target.send_keys(template)
                     clean = target.get_attribute('value') == template
                 
-                flow.do(Wait)
-                flow.react()
+                flow.react(Wait)
                 box = locate("div.io-ox-mail-compose-window .mail-input .tokenfield .token")
                 recipient = box.get_attribute('innerText').strip()
 
@@ -527,10 +517,10 @@ def main(driver: Chrome, logger = logging.getLogger('main')):
                     logger.warning('Malformed email content detected; retrying (%d)...', attempts)
                     continue
 
-                flow.do(Wait)
-                flow.react()
+                flow.react(Wait)
                 click("div.io-ox-mail-compose-window button[data-action='send']")
             except Skip:
+                progress['skip'] += 1
                 index += 1
                 attempts = 0
                 continue
@@ -566,13 +556,11 @@ def main(driver: Chrome, logger = logging.getLogger('main')):
 
         if options.get('writable'):
             try:
+                logger.info('Saving document...')
                 status = Status.CLOSING
                 flow.allow(Wait, False)
-                flow.allow(Timeout)
                 flow.allow(Close)
-                logger.info('Saving document...')
-                flow.do(Timeout, force=True)
-                flow.react()
+                flow.react(Timeout)
             except Close:
                 pass
             except Exception as e:
diff --git a/requirements.txt b/requirements.txt
index 309abe7..a938230 100644
Binary files a/requirements.txt and b/requirements.txt differ